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Current Trends Congenital Syphilis -- United States, 1983- 1985
After 8 years of steady decline, the number of reported cases of congenital syphilis (CS) among persons under 1 year of age rose in the period 1978-1985 from 108 to 268 (Figure 1). Incidence of CS generally reflects incidence of primary and secondary (P & S) syphilis among women of childbearing age, as well as the diagnosis and treatment of syphilis in prenatal care programs. In 1985, rates of CS were highest in areas with high incidence of P & S syphilis (1) (Figure 2). Three states (Texas, Florida, California) and one major metropolitan area (New York City) accounted for 80% of all CS cases reported in 1985. Between 1978 and 1983, P & S syphilis rates for women also increased to a peak of 7.6 cases/100,000 women in 1983 (Figure 1).
In 1983, CDC surveillance of CS was modified to enable the reporting of detailed clinical data on affected infants and their mothers to the Division of Sexually Transmitted Diseases, CDC. On the basis of these data, reporting areas classified CS cases among patients less than 1 year of age by a modification of previously published criteria (2) as "definite," "probable," "possible," and "unlikely." This information for the period 1983-1985 was used to explore what factors could be associated with the trend toward rising incidence.
Clinical data and certainty of diagnosis are available for 460 patients (111 cases reported in 1983, 209 in 1984, and 140 in 1985). Fifty (11%) patients with clinical information had dark-field-proven "definite" CS, and 191 (42%) were classified as having "probable" CS on the basis of rising serologic titers prior to treatment, persistently positive treponemal tests at 6 months of age, or major clinical manifestations. Of these patients, 10 were seronegative at birth, but each was retested when the mother was seen for secondary syphilis during the child's infancy. One hundred ninety-six (43%) were classified as having "possible" CS on the basis of minor clinical criteria and positive serologic testing. Six of the infants tested were considered to have a low risk of infection ("unlikely" CS) because the mothers had adequate treatment during their pregnancy and the infants were asymptomatic at birth. For 17 (4%), insufficient data existed to establish the certainty of diagnosis.
Of the 460 case-infants, 238 (52%) were black; 167 (36%), Hispanic; 40 (9%), white; 15 (3%), other or unknown race. The mean age of case-infants at the time of reporting was 2.1 months; 276 (60%) were reported as having CS in the first 30 days after birth.
Stillbirth in the presence of maternal early syphilis was the initial symptom prompting evaluation for 21 (19%) of the infants reported in 1983, for 74 (35%) of the infants reported in 1984, and 40 (29%) of the infants reported in 1985. In 30% of reported cases in all three of these years, infants were born with symptoms suggestive of CS. Only 12% of infants were asymptomatic at birth and diagnosed solely because of a positive maternal delivery serologic test for syphilis (STS).
Osteochondritis and periostitis were the most common major signs of CS in this series. Jaundice, hepatosplenomegaly, and cutaneous lesions were the most frequently cited minor (non-specific) signs of CS. Clinically significant central nervous system involvement was identified in 34 cases, but only five infants had cerebrospinal fluid serologic evidence of neurosyphilis.
Demographic characteristics of mothers of infants with CS did not change appreciably over the 3 years studied. The mean age for a mother at the time of birth of the infected infant was 24 years (range, 14-43 years); 133 (30%) mothers were under 20 years of age.
In the general population, 95% of pregnant women have at least one prenatal medical visit (3); in contrast, only 52% of mothers of infants with CS reported having at least one prenatal visit (Table 1). Among those mothers receiving prenatal care, the mean gestational age at which they were first seen for prenatal care was 22 weeks--i.e., late in the second trimester.
Preventable failure to diagnose or treat infected mothers who did receive prenatal care contributed to the occurrence of CS. Of women who received prenatal care, CS cases were attributed to failure to screen for syphilis (18 women, 8%); failure to treat pregnant women with reactive STS (32 women, 14%); and failure to screen women in the third trimester of pregnancy who lived in an area of high CS prevalence (58 women, 25%) (Table 1).
Of the 229 women who received prenatal care, 81 (35%) were treated for syphilis during their pregnancies but later had infants with CS (Table 1). Sixty of these treatment failures occurred among women who had been treated with benzathine penicillin regimens appropriate for their stage of infection; 45 of these were in the third trimester and another 11 in the second trimester. In three of the second-trimester treatment failures, a reinfection was documented in the third trimester. Thirty-five percent of the treatment failures occurred among mothers who were treated during the P & S stages of syphilis and later had infected infants. Of the untreated group, only 24% were in the P & S stages of syphilis at the time of diagnosis. Erythromycin oral regimens used for pregnant patients who reported a penicillin allergy accounted for 11 of the 81 treatment failures. Reported by Epidemiology Research Br, Evaluation and Statistical Svcs Br, Div of Sexually Transmitted Diseases, Center for Prevention Svcs, CDC.
Editorial note: Steady decreases in incidence of CS occurred following the introduction of benzathine penicillin therapy in the 1950s and prenatal serologic screening for syphilis (4). However, substantial increases in reported cases have been observed in recent years.
Part of the increase observed in 1984 may be attributed to increased sensitivity of the surveillance system--particularly for stillbirths. However, there is no trend to suggest that the increase observed in 1985 is attributable to any change in reporting activity. The recent increases in CS incidence suggest that increased vertical transmission may be related to under-utilization and inadequacy of prenatal care. With high rates of P & S syphilis still existing in some areas in the United States, it is particularly important to provide early, high-quality prenatal care to populations in these areas, with serologic testing in both the first and third trimester (5) and adequate follow-up to detect reinfection and treatment failure.
Clinical data on confirmed CS cases in the series reported on here suggest that at least 60% of cases could have been prevented if the above recommendations had been implemented. The resources required for accessible, high-quality early prenatal care to adequately screen pregnant women for syphilis are considerable. However, even in female populations with very low prevalence of early syphilis, prevention in the prenatal care setting is cost-effective (6).
Complete reporting of those infants who may be infected is essential to the surveillance and ultimately the prevention of CS. The data indicate that CS cases are being reported very shortly after birth, underscoring the timeliness of the surveillance system. When mothers develop symptoms of syphilis within 12 months after their babies are born, the infants should be evaluated even if they were seronegative at birth (2).
Failure of recommended prenatal antibiotic treatment regimens resulted in 19% of the confirmed CS cases in this series. Of these, third-trimester treatments and erythromycin treatment due to maternal penicillin allergies accounted for 69% of failures. Erythromycin treatment during pregnancy has been associated with numerous reports of treatment failure (7,8). For pregnant women who are allergic to penicillin, oral desensitization after documentation of penicillin allergy represents a promising alternative (9). Further evaluation of treatment failures during P & S stages of syphilis, as well as during the third trimester, is under way to determine the adequacy of current recommendations and to provide guidelines for theoretical alternative antibiotic regimens.
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